This paper describes the latest safety and performance monitoring techniques that are being employed on structures and vessels engaged in Canadian offshore oil and gas exploration projects. The rationale behind the installation of any type of monitoring system on an offshore structure, is that it will provide information about the parameters which have significant influence upon its stability or operational performance. This information is used for ensuring the safety of the operating personnel on board the structure, for assessing the integrity of the structure, and for facilitating design modifications. For this reason it is essential that the sensors and the data gathering systems are selected and installed in such a manner that they are capable of reliably detecting changes in the most fundamental stability parameters available for examination. The results of a number of recent monitoring programmers are discussed in terms of the following parameters and their interrelationships at sites in the Canadian Beaufort.
Inelastic displacements of the structure, both absolute and relative.
Change of load within the structure, both external and between adjacent components.
Changes of state of strain in the structure, both elastic and inelastic.
Variations in the dynamic response of the structure.
Geotechnical, including piezometric, total pressure and permafrost effects.
The paper concludes with a description of the acquisition software necessary to provide useful data for both the operation and regulation of offshore drilling systems.
Over the past decade, an enormous investment has been made in the exploration programs being carried out by various companies and joint ventures, particularly in the Canadian Beaufort. This search for oil has, of course, shifted northward as the demand for more reserves and supply sources has increased and changed. This shift of activity into more severe climates and extreme conditions has caused an increase in emphasis on the development of technology which is appropriate for the operation of permanent or semi-permanent structures under these conditions. As a result, various aspects of this technology, which are currently unique to Canada, can be considered to be at the very early stages of development. There still remains an enormous potential for the development of the various technologies and methodologies which will be necessary for exploration, and exploitation, in the frontier areas.
In the past, the purpose of monitoring programs has been to provide the operators of these structures with relevant and current information about the probable integrity and stability of the various components of the structure, as well as of the structure as a whole. Typically, a synopsis of this information would be made available in a graphical or visual form rather than in a numerical one, as the significance of trends and peak events is more readily comprehensible when presented in this form to operating personnel with many other demands on their time.
In the majority of exploration or production structure monitoring programs, the primary areas of interest can be summarized as follows:
Artificial Foundations (subsurface berms)